1. Field of the Invention
The present invention relates generally to a vehicular number plate including luminous characters, numerals or similar marks. More particularly, the present invention relates to a number plate of the foregoing type which assures that character portions on the number plate are illuminated uniformly more than those of a conventional number plate, the number plate has excellent durability, and moreover, it can easily and simply be fabricated.
2. Description of the Related Art
A hitherto known number plate including luminous characters, numerals or similar marks (hereinafter referred to simply as a luminous number plate)is typically constructed as shown in FIG. 5 and FIG. 6. Specifically, the luminous number plate includes a flat case 1 to which an openable frame 2 is turnably fitted. A front plate 4 coated with a paint having a specified color is attached to the frame 2 to serve as a so-called number plate by tightening set screws. The front plate 4 has a plurality of character portions 3 punched therefrom to which character-like plates 31 each molded of a transparent synthetic resin are adhesively secured. To illuminate the character portions 3 at night, two bulbs 5 are disposed inside of the flat case 1.
With the conventional luminous number plate as constructed in the above-described manner, when the character portions 3 are illuminated by the bulbs 5, they can visually be recognized from remote locations. However, it has been found that the conventional luminous number plate has a drawback that the respective character portions 3 are illuminated in a different manner such that the character portions 3 located directly above the illuminating bulbs 5 are brightly illuminated but the character portions 3 located remote from the illuminating bulbs 5 are illuminated with reduced brightness.
In view of the foregoing drawback, at present, a translucent milk-white light scattering plate 7 (see FIG. 7) having black paints 6 coated and baked in the region corresponding to the illuminating bulbs 5 while having a thickness gradually reduced toward the peripheral part thereof is interposed between the front plate 4 and the bulbs 5 so as to allow a quantity of light beam measured directly above the bulbs 5 or in the vicinity of the same to be reduced in order to assure that the character portions 3 are uniformly illuminated (refer to an official gazette of Japanese Utility Model publication No. 16,308/1978).
However, when the black paints 6 are peeled away from the scattering plate 7 or one of the bulbs 5 is turned off for some reason, there arises another drawback that all characters 31 on the character portions 3 are irregularly illuminated, and moreover, they are hardly visually recognized by anybody.
To obviate the foregoing drawback, a luminous number plate having phenomenon of electroluminescence employed as a light source has been developed. Specifically, this luminous number plate is constructed such that character portions are punched from a front plate, character-like plates each molded of a transparent or translucent synthetic resin are adhesively fitted into the character portions, a single electroluminescent plate is disposed behind the character portions so as to allow the latter to be illuminated with the electroluminescent plate, a DC/AC inverter electrically connected to a power source for a vehicle is attached to the rear surface of the electroluminescent plate, and two electrodes each extending across the substantially whole length of the electroluminescent plate are electrically connected to the DC/AC inverter at the opposite of the luminous number plate as viewed in the longitudinal direction.
With the luminous number plate having the electroluminescent plate arranged in that way, however, since the electroluminescent plate is arranged on the whole surface of the luminous number plate in the longitudinal direction, another drawback is that the luminous number plate is fabricated at an expensive cost. In addition, since the whole electroluminescent plate should be replaced with a new one when the luminous number plate is replaced with another one for some reason, an additional drawback is that the luminous number plate is fabricated at an unacceptable economical efficiency. Additionally, since the electroluminescence plate is designed with large dimensions, it is anticipated that there arises another drawback that a load to be borne by the luminous number plate in association with an electric current applied thereto is hardly uniform, resulting in the respective character portions being hardly uniformly illuminated by the electroluminescent plate.